1. Field of the Invention
The invention relates to a method for producing a window frame consisting essentially of plastic section pieces welded together.
The invention also relates to a window frame obtained using said production method.
2. Description of the Related Art
First of all, the expression xe2x80x9cwindow framexe2x80x9d is understood as meaning the fixed or opening frame of a window or a window jamb.
In general, a window comprises at least one pane of glass assembled with a mobile or non-mobile bearing frame hung on a jamb which is fixed into the stonework.
Conventionally, the window frame consists of a number of section pieces joined together in such a way as either to surround the opening made for this purpose in the stonework or to take a pane of glass, the section pieces therefore exhibiting a housing designed for this purpose and known as the glazing rebate.
When the window frame is made of plastic such as, for example, polyvinyl chloride (PVC), the section pieces are generally joined together by thermal welding at the corners of said frame. This assembly takes place by melting the plastic of each section plane over a few millimeters before clamping the section pieces together to obtain a weld. The clamping compresses the molten parts and causes a bead of material to form in the region of the join, this bead of material protruding from the visible surfaces of the frame. The welded parts then have to be deburred in order to eliminate the unattractive surplus material.
This method, although commonly employed, has a certain number of drawbacks which it would be desirable to alleviate, at least in part.
First of all, the result of such a method is that the desired final dimensions of the welded frame are not precisely achieved and generally vary by plus or minus 1 mm.
Thus, when, for example, the glazing is immobilized in the frame by attached glazing beads which are fixed to the frame by clipping or any other means of attachment known to those skilled in the art, each glazing bead has to be cut to the precise dimension observed after welding so that it fits perfectly in the frame.
In consequence, a product such as this generates a great many operations and involves a great deal of labor for implementing it.
What is more, it entails the carrying of a large stock of parts for making the frame and entails very precise management.
What is more, the removal of surplus material from the regions of the joints involves a lot of material in addition to the corresponding process time, and this further affects the profitability of the method.
The object of the present invention is to improve this type of manufacture.
The subject of the invention is therefore a novel method for producing window frames consisting essentially of plastic section pieces welded together which is easy to implement, which reduces the number of operations, and which makes stock management easier.
The invention proposes a method for producing a window frame consisting essentially of plastic section pieces welded together, such that the section pieces are cut so that at least part of the section of said section pieces determines the required length of the section pieces, and then the section pieces are thermally welded together, avoiding welding those parts of the sections of the section pieces that determine the required length of the section pieces.
The term xe2x80x9crequired lengthxe2x80x9d is to be understood as meaning the length of the section pieces, determined to within one millimeter, so as to produce the frame once the section pieces have been assembled.
As a preference, those parts of the sections of the section pieces that determine the required length of the section pieces act as limit stops during assembly by thermal welding.
Thus, having melted part of the ends of the section pieces, the clamping of the section pieces is blocked in its travel by the unwelded parts of the section pieces, and the assembling of the section pieces makes it possible to obtain a frame, the dimensions of which are precisely predetermined. Thus, any prefabricated additional component can be fitted without the need to measure the dimensions of the assembled frame after assembly in order to adjust the dimensions of the additional part.
According to a preferred embodiment of the invention, the section pieces are cut while at the same time making at least one offset on the lateral sides of said section pieces, said offset determining the required length of said section pieces.
Thus, at the time of assembly, the lateral sides of the section pieces come edge to edge without being welded together, and the appearance of surplus material that needs to be eliminated is avoided.
According to another embodiment of the invention, the section pieces have at least one glazing bead integral with said section pieces and movable, and the section pieces are cut while at the same time making at least one offset at the glazing bead, said offset determining the required length of said section pieces.
Thus, the section pieces are joined together up to the point where the glazing beads come edge to edge. The frame obtained thus has the predetermined dimensions, the glazing beads determining the required length.
According to another alternative form of the invention, the section pieces are cut while at the same time making at least one offset in the region where a seal is to be positioned, said offset determining the required length of said section pieces.
The section pieces may be fitted with the seal after they have been assembled into the form of a frame, or alternatively before assembly, the seal possibly being coextruded onto the section piece at the time of the manufacture of the latter.
As a preference, the seal is a seal extruded separately (extruded xe2x80x9cby the kilometerxe2x80x9d), that is cut to the required length of the section piece before being fitted on the section piece in the positioning region designed for this purpose, aligning the ends of the seals with the offsets in said region.
In this alternative form, assembly is performed while avoiding the welding of the section pieces in the region in which the seal is positioned.
Thus, when assembling the section pieces, the welding of the seals and thus the appearance of excess material at their point of contact is avoided. All that is then required is for the free ends of the seals to be bonded together so as to seal the assembly.
According to a preferred embodiment of the invention, which is applicable to each embodiment or alternative form described hereinabove, the offset is between 1 and 3 mm.
According to one alternative form of the invention, a plastic or metal section piece is incorporated into the section pieces that form the window frame, this incorporated section piece having the required length of the section pieces so that it acts as a stop piece during assembly by thermal welding.
Another subject of the invention is a novel window frame that can be obtained from the production method described hereinabove.
The invention proposes a window frame essentially consisting of plastic section pieces welded together, such that the assembly surface of the section pieces exhibits at least one region which is not welded.
Thus, at the time of assembly, part of the section of a section piece is welded to a corresponding part of the section of a second section piece, and the remainder of the section of the section piece is simply in edge-to-edge contact with the corresponding remainder of the section of the second section piece.
According to an advantageous alternative form of the invention, the unwelded region is at least the lateral sides of said section pieces.
Thus, when the section pieces are assembled, the welded point is made in a part of the section pieces which is not exposed to view and there are no longer any regions of finish-grinding on the lateral sides, said region of finish-grinding corresponding to the deburring of the excess material resulting from the welding operation. Thus, the region of assembly is near the practically invisible region of the lateral edges.
According to a preferred alternative form of the invention, the section pieces have a double wall in the region of the lateral sides, the two walls being spaced apart, and the unwelded region is the outer wall of the double wall.
Thus, there is still one welded wall in the region of the lateral sides, which makes it possible to guarantee the leaktightness of the assembly and good overall weld strength, particularly in terms of resistance to breaking at the corners. Furthermore, the space between the two walls is able to catch the excess material that results from the welding operation, so that good edge-to-edge contact of the outer wall can be maintained, without the need for deburring.
According to an alternative form of the invention, the section pieces exhibit at least one glazing bead integral with said section pieces and mobile, and the ends of the glazing beads are not welded together.
According to an advantageous alternative form of the invention, the unwelded region of the section pieces is at least the region in which a seal is to be positioned. Thus, at the assembly surface, there is no node that corresponds to the welding together of the seals, such a node being unacceptable and having, of necessity, to be removed.
As a preference, the seals are bonded together at their ends. Thus, sealing is achieved around the entire periphery of the frame.
According to one embodiment of the invention, a plastic section piece is incorporated into the section pieces constituting the window frame, said plastic section piece having the same length as the assembled section pieces and not being welded at the time of assembly.
According to another embodiment of the invention, a metal section piece is incorporated into the section pieces constituting the window frame, said metal section piece having the same length as the assembled section pieces.
According to an advantageous alternative form of the invention, said incorporated section piece is a casement bolt.
The frame thus obtained advantageously has dimensions which are predetermine to within one millimeter, is easy to implement and simplifies the production method.